C# – LINQ to Entities does not recognize the method ElementAt(i);

centityentity-frameworklinq

I'm using the method elementat(Int32) to get a specific element of a query's result.

var mds = db.TDP_MissioniDestinazioni.Where(p => p.MissioneID == missioneRow.MissioneID);  

destinazioneRow = mds.ElementAt(i);

LINQ to Entities does not recognize the method
'TimeEntModel.TDP_MissioniDestinazioni
ElementAt[TDP_MissioniDestinazioni]
(System.Linq.IQueryable`1[TimeEntModel.TDP_MissioniDestinazioni],
Int32)' method, and this method cannot be translated into a store
expression.

Why am I getting this error and how can I fix it?

Best Answer

Are you happy to fetch all the "earlier" results? If so, either call ToList() to cache them, or AsEnumerable() to fetch them on each call, with the AsEnumerable just being a way to force the compiler to call Enumerable.ElementAt instead of Queryable.ElementAt.

There may be a better way (e.g. using Take or Skip) though - could you give more information about the bigger picture?

Related Solutions

C# – LINQ to Entities does not recognize the method ‘Int32

You can split your query in two to make sure the list is in-memory before calling the GetNumberOfDevices() method. You can make a query in-memory by converting the results to a List, or in this case a List<GetFreeDevices>. That way, LinQ to Entities does not have to do any translations to and from XML and you can use your GetNumberOfDevices() method.

var view_query = (from i in query
     select new GetFreeDevices
     {
        MArticleNumber = i.ArticleNumber,
        MFirmware = i.Firmware,
        MGroup = i.Group,
        MName = i.Name,
        MSoftware = i.SoftwareVersion

     }).ToList();
var result_query = from i in query
     select new GetFreeDevices
     {
        MArticleNumber = i.MArticleNumber,
        MFirmware = i.MFirmware,
        MGroup = i.MGroup,
        MName = i.MName,
        MSoftware = i.MSoftware,
        SA = GetNumberOfDevices(i.MArticleNumber,2),
        STH = GetNumberOfDevices(i.MArticleNumber,3),
        SASTH = GetNumberOfDevices(i.MArticleNumber,7)
     };
return PartialView(result_query);

Please note that the last statement requires the PartialView to accept a list or IEnumerable instead of an IQueryable.

C# – LINQ to Entities with AddMonth method

You can use SqlFunctions classvar;

 today =  DateTime.Now; return Newsletterctx.Subscribers.Count(o =>
 o.Validated == false &&
 o.ValidationEmailSent == true &&
 SqlFunctions.DateAdd("month",1,o.SubscriptionDateTime) <today);

Best Answer

Related Solutions

C# – LINQ to Entities does not recognize the method ‘Int32

C# – LINQ to Entities with AddMonth method

Related Topic